The invention relates to a device for mounting plastic sheets, especially plastic nap sheets, on panes, sashes and so on, of walls, roofs, etc. of greenhouses or other heated buildings with large windowpanes.
In connection with the heating of greenhouses the use of nap sheets for heat insulation is becoming increasingly important for saving energy. Generally, nap sheets consist of three superposed plastic films, the intermediate of which is fixed partly to the bottom film and partly to the top film so that small, substantially closed, air-filled flat cushions are formed between the films. Therefore, these nap sheets have a high thermal insulating property and are used for the temporary heat insulation of greenhouses, as well as other insulation purposes. Until now, the sheets have mostly been fastened on the inside of the greenhouse wall or roof by means of holders which are pasted on the pane or screwed onto the aluminum sashes supporting the panes. The attachment of nap sheets to the inside of the wall or roof usually results in a difficult and tedious mounting procedure because of shelves, heating pipes, etc. located inside the greenhouse. Moreover, it is difficult to seal leaks by covering the walls with sheets from the inside. Additional time is wasted by the need to repeatedly remove and remount the sheets, e.g., in spring and in autumn.
Known devices for mounting nap sheets are designed in such a manner that the nap sheet is fastened by putting it on a holder and screwing a cap on the holder. These devices are not suitable for mounting sheets on the outside of greenhouses because the sheets easily tear out by the action of wind and consequently detach from the mounting device. The outdoor fastening is, however, desired because of improved insulation and the easier mounting of the sheets.
An object of the present invention is to provide a device for mounting plastic sheets, especially plastic nap sheets, on glass panes and/or sashes which form portions of walls, roofs, etc. of buildings, such as greenhouses with large glass panes.
A further object of the invention is to provide a device for the outdoor mounting of plastic nap sheets on panes and/or sashes which resists strong wind action and prevents tearing out of the sheet at the fastening points.
A further object is to provide a device for mounting nap sheets at pane walls and/or pane roofs which avoids twisting of the sheet at the mounting point such as occurs with the known screw devices when screwing on the cap. This twisting causes an undesirable stress of the plastic sheet material which facilitates tearing out under wind pressure.
A further object of the invention is to provide a device for fastening nap sheets at panes and/or sashes which facilitates the rapid mounting and demounting of the sheets and allows quick accommodation of the thermal insulation to the weather conditions.